Method and apparatus for producing twisted plastic fibre of predetermined length



H T G m D L7 L 0% I. 0 M? D m 0 mt ME m M F Jan. 13, 1970 METHOD AND APPARATUS FOR PRODUCING TWISTED PLASTIC .D B m wN 0 0 MA M s a m I L E A H m M m aau i m gamma HTIO/QNE Y United States Paten US. CI. 57-34 ABSTRACT OF THE DISCLOSURE A method for producing twisted lengths of plastic fibre wherein filaments on storage reels are'drawn from the reels while the reels are rotated transversely to the unreeling direction to twist a single filament, or twist ply multiple filaments. The twisted filaments are drawn through heating, then cooling, means andcut to length. An alternative method twists filaments strung between spaced frames, heat sets, cools and cuts the filaments. Apparatus for performing the method includes rotatable cages to support, and rotate, the reels, and feed rollers for drawing and filaments off of the reels and through heating, cooling and cutting means.

This invention relates to a method for forming spiralled or twisted synthetic plastic fibres, and in particular, the invention provides spiralled or twisted plastic fibres suitable for use in brooms, brushes, sweepers and the like.

It is known to provide synthetic fibres for the aforementioned uses, in the form of straight non twisted fibres or crimped fibres.

It is known to mount these fibres in the sweeper head of a road sweeping machine, wherein the sweeper head comprises a cylindrical wooden drum provided with a spiral groove extending over its length. The fibres are doubled at their centres and held to the drum by a rope wound into the groove through the folded fibres.

In another form, the fibres are clamped between a pair of steel plates so that they extend radially from the centre.

In the case of yard brooms, brushes and the like, the fibres may be tufted into the broom or brush head in the known manner.

A problem that arises in the known form of the fibres is that, when subjected to stresses, strains and temperature changes in use, the fibres tend to splay and spread. This effect is due to a memory function possessed by the synthetic plastic whereby the original curl which was impressed on it when the material was originally stored in rolls in filamentary form, tends to return to the fibres, notwithstanding subsequent processing and mounting of the fibres.

A further disadvantage which has been found in the use of the known sweeper heads particularly when mounted in street sweeping machines, is that the straight fibers are not inherently resilient in the direction of their length, so that the sweeper head tends to bounce and be deflected by any uneven parts of the surfaces being swept.

In an attempt to overcome this, it is known to crimp the fibres in order to provide some longitudinal resilience, but the beneficial effect of such crimping is limited particularly in regard to subsequent splaying, curving or bending in use.

It is an object of the present invention to provide synthetic plastic fibres which will be more resilient and wherein splaying, curving or bending of the mounted fibres, in use, is prevented.

It is still a further object of the present invention to 3,488,934 Patented Jan. 13, 1970 ice provide fibres which are adapted to be more securely mounted in the sweeper head, by reasonof their configuration.

It is a still further object of the invention to provide a method of producing such spiralled or twisted synthetic plastic fibres.

Accordingly, one aspect of the present invention comprises a method of forming twisted plastic fibre wherein at least a pair of synthetic plastic filaments are twisted together by a twist force imparting means, drawn firstly through heating means to stabilise the filaments in twisted relationship wherein each filament has a spiral or twist formed therein and about the other, through a cooling means and then cut to predetermined length.

The twist force may be imparted by a rotating cage on which the filaments are stored on reels rotatable about axes transverse to the axis of rotation of the cage the filaments being drawn from the rotating cage in adjacent relationship through a guide tube, die or rollers before entering the heating means. Alternatively it it is desired to prevent the twist forming back onto the storage reels, a further rotatable cage is provided wherein the filaments passing from the storage reels are led over two pairs of pulleys or rollers rotatable about axes transverse to the axis of the cages. This further cage may be attached to the storage cage for rotation therewith.

According to another aspect of the invention the twisted filaments are divided into at least a pair of separate plastic fibres, each having a spiral or twist formed therein, either prior to being cut to length, or subsequently thereto.

According to yet another aspect of the invention one filament only is twisted in the method of the invention by utilising only one storage reel at a time.

The invention also consists in synthetic plastic fibres, or filaments formed by the methods in spiralled and/or twisted configuration, for use in brooms, brushes, sweepers and the like.

The invention further provides an arrangement for carrying out the method of the invention, such arrangement comprising twist force imparting means, heating means, cooling means, feeding means and cutting means.

In order that the invention and its manner of performance may be more fully described, reference will now be made to embodiments of the invention illustrated in the accompanying drawings in which:

FIGURE 1 illustrates a layout of an arrangement for carrying out the method of the invention;

FIGURE 2 is another view of the storage cage of FIG- URE 1;

FIGURE 3 illustrates a part of the arrangement of FIG- URE 1 showing the twist force imparting means as an additional part to the storage cage;

FIGURE 4 is another view of the twist force imparting means of FIGURE 3);

FIGURE 5 illustrates a length of a pair of twisted filaments of the invention; and

FIGURE 6 illustrates a length of a single twisted filament.

Referring to the drawings, the synthetic plastic fibre material 5 is stored on reels 6 freely rotatable in a cage 7 having journals 8 and 9 mounted in bearings 10, said cage being rotatably driven by motor means 11 through a chain 12 and sprockets or the like driving means. The filaments 5 may be of polypropylene, high density polyethylene, polystyrene, terylene or nylon, and may be of round, oval, fiat or other suitable cross-section.

The filaments 5 pass from storage reels 6 through journal 8 which is provided with a passageway 13 acting as a guide tube or die. Rotation of cage 7 twists the pair of filaments around each other and rollers 16 draw the twisted filaments through a heating means 14 wherein the twist is thermoset and stabilised in the filaments and then through a cooling means 15. Cutter 17 operates to cut the cooled stabilised twisted filaments 19 into predetermined lengths which are collected for subsequent bundling in container 18.

Although the twisting of the filaments together normally takes place in or adjacent passageway 13, the twist may in some cases be carried back to reels 6. This is not altogether detr miental but to obviate the carry back of the twist, a further cage 23 may be attached to journal 8 as shown in FIGURES 3 and 4. This cage 23 is provided with two pairs of freely rotating rollers or pulleys 21 and 22 over which the separate filaments 5 are led thereby ensuring that the twist cannot be carried back even through cage 23.

If it is desired to separate the pair of twisted filaments 19 into separate twisted and spiral filaments, a separating stage may be incorporated in the arrangement of FIGURE 1 either before cutting or after cutting. Any conventional separating means may be utilised.

FIGURE 6 illustrates a single twisted filament 20, twisted about its axis as distinct from a twisted/ spiral filament separated from a pair as above described. This filament 20 is formed by the same arrangement as in FIG- URES 1 to 4 by using only one storage reel 6 at a time andusing only one each of the pairs of rollers 21 and 22. By forming a single twisted heat stabilised filament 20 in this manner any tendency of the filament to curve, bend or splay in use is prevented. Whilst a short section of a length may tend to bend in one direction, the next adjacent section acts to cancel this bending and so on, and throughout the requisite length of the filament 20 in this stabilised twisted form any tendency to bend or curve is neutralised.

An alternative method of forming a single twisted filament comprising the steps of twisting the filaments separately on relatively rotatable steel frames in a tight fashion,

applying heat as by hot air, cooling the stabilised twisted I filament for a short .period and then cutting .to the desired length.

The spiralled or twisted fibres or filaments formed by the methods of the invention, are particularly useful in the application to road sweepers, since the fibres or filaments are readily secured to the sweeper head by any of the known means, and the twist or spiral effects a more secure attachment of the fibres or filaments to the head. Furthermore, the hitherto inherent defect whereby the known fibres or filaments become splayed, curved or bent because of the memory retention properties of the plastic, is overcome, since the inherent curl of the fibre or filament is absorbed in each spiral turn or twist imparted to the plastic fibres or filaments. Consequently, the overall curl is compensated and the fibres or filaments remain straight under the conditions of use.

I claim:

, 1. A method of forming twisted plastic fibre comprising, drawing a filament from a storage reel while rotating the reel about an axis transverse to the axis of unreeling I 2. A method of forming twisted plastic fibre as claimed in claim 1 wherein, drawing a second filament in adjacent relationship with the first mentioned filament from a second storage reel while rotating the second reel about an axis transverse to the axis of unreeling rotation and in alignment with the transverse rotational axis of the first reel to impart a twist to the second filament and twist the filaments about one another prior to heating and coolmg.

3. A method of forming twisted plastic fibre, as claimed in claim 2 wherein, the filaments are drawn from the reels in adjacent relationship by passing them through guiding means.

4. A method of forming twisted plastic fibre as claimed in claim 3 wherein, the filaments are held separated adjacent the guiding means to prevent twist run-back to the storage reels.

5. Apparatus for forming twisted plastic fibre comprising, a cage rotatable about an axis, at least one filament storage reel mounted in the cage for rotation about an axis transverse to the cage rotation axis, heat stabilising means, cooling means, means to cut the filament into predetermined lengths, and means to draw the filament from the reel in the direction of the cage rotation axis and through the heat stabilising and cooling means to twist the filament and 'set it and move the set twisted filament to the cutting means.

6. Apparatus according to claim 5 wherein a filament guide member is located between the storage reels and the heat stabilising means.

7. Apparatus according to claim 6 wherein the guide member comprises a hollow journal of said cage.

8. Apparatus according to claim 7 including a further rotatable cage attached to said hollow journal, said further cage having two pairs of rollers rotatably mounted thereon on axes transverse to the axis of rotation of said further cage and around which the filaments pass from said storage reels before twist is applied.

References Cited UNITED STATES PATENTS 3,379,003 4/1968 Kanbar 5734 XR 3,383,850 5/1968 Ratti 57157 1,983,326 12/1934 Taylor 57157 XR 1,988,586 1/1935 Deacon 5759' XR 3,086,252 4/1963 Marley 19-.6 XR 2,862,350 12/1958 King et al. 5734 2,863,280 12/1958 Ubbelohde 57-157 3,327,461 6/1967 Wyatt 5734 3,364,289 1/1968 Campbell 57160 XR 3,368,335 2/1968 Horvath 57-34 3,239,867 3/1966 Charvat.

3,382,657 5/1968 Horvath 5734 DONALD E. WATKINS, Primary Examiner Us. (:1. X.R. 

